浆态床费托合成分离系统的流程模拟与优化

Process simulation and optimization for separation system of Fischer-Tropsch synthesis with slurry reactors

针对目前浆态床费托合成工业装置中分离系统运行中出现的尾气换热分离器换热性能差、重质油带水、易堵塞等问题,通过流程模拟对神华宁煤400万吨/年费托合成装置的分离系统进行了分析。模拟结果表明,现运行工况下换热器冷侧气体最低温度(70℃)远低于水蒸汽露点温度(123℃),因此局部换热不均时会造成热气体过冷,从而导致水蒸汽冷凝、重质蜡和催化剂粉沫黏附堵塞。在模拟分析的基础上提出了两级换热流程,保障换热分离器在露点温度以上操作,避免重质油带水和堵塞问题;模拟结果表明,新流程可降低单系列尾气空冷器负荷32 MW,增加单系列反应器蒸汽产量49 t/h,降低全厂年生产成本1亿元左右,节能增效显著。

The heat exchanger & separator for Fischer-Tropsch reaction tail gas is one of the key equipment.In the real operation, it indicates poor heat transfer performance, heavy oil with water and easy blockage which restricts the long-term operation of Fischer-Tropsch synthesis unit. For this problem, by the process simulation and field operation data analysis, the results show that the lowest gas temperature(70 ℃) at the cold side of the heat exchanger is far lower than the dew point temperature(123℃) at the current condition.Once the local heat transfer is not uniform, it is easy to make the hot gas supercool and lead to steam condensation, heavy wax and catalyst powder adhesion blockage. For this reason, a two-stage heat exchange process is proposed, to ensure the operation of the heat exchanger separator above the dew point temperature and avoid the problems of heavy oil with water and blockage. The simulation results show that the new process can also reduce the load of the single series tail gas air cooler by 32 MW, and increase the steam output of the single series reactor by 49 t/h. The annual production cost of the whole plant can be reduced by about 100 million yuan, which has a remarkable energy and cost saving.